Color sensing (as well as detecting empty spaces) settled on IR-based sensors commonly used in line-following robots. You can watch the clock in action in the video embedded below just under the ...
The sensor measures cookware temperature through ceramic glass improving induction hob precision safety & automation for better cooking control ...
Or you can go back to basics and build this reflective RGB sensor from an LED and a photocell. The principle behind [TechMartian]’s approach is simplicity itself: shine different colored lights ...